From: "James A. Donald" <jamesd@echeque.com>
Date: Sat, 21 Oct 95 15:49:50 PDT
To: Thomas Grant Edwards <kelso@netcom.com>
Subject: Re: Anonymity: A Modest Proposal
Message-ID: <199510212249.PAA22804@blob.best.net>
MIME-Version: 1.0
Content-Type: text/plain


At 12:59 PM 10/19/95 -0400, Thomas Grant Edwards wrote:
>This would require the remailer to examine entropy of messages passing 
>through.  Anything not random enough gets tossed.


A simple entropy measuring algorithm:

Generate N random pointers into a file. (or extract N random short 
strings from the file)

Sort them into order of the strings,

Find the number of bits in common between one string and the 
next string.  Total up S, the number of bits in common

Calculate (N * lg N)/S

For an encrypted file, this quantity should be close to unity, because 
the order in an encrypted file should not be easily detectable.


 ---------------------------------------------------------------------
              				|  
We have the right to defend ourselves	|   http://www.jim.com/jamesd/
and our property, because of the kind	|  
of animals that we are. True law	|   James A. Donald
derives from this right, not from the	|  
arbitrary power of the state.		|   jamesd@echeque.com